Systems for cooling motors of refrigerant compressors



Oct. 9, 1962 J. L. DITZLER SYSTEMS FOR COOLING MOTORS OF REFRIGERANT COMPRESSORS Filed April 3, 1961 GEAR MOTOR BOX nits This invention relates to hermetically-sealed, refrigerant compressor-motor units, and has as an object to cool the electric motors within and used for driving the compressors of such units, with saturated refrigerant gas.

It is the general practice to cool the electric motors of hermetically-sealed, compressor-motor units with suction gas passing from associated evaporators to the suction sides of the compressors. Disadvantages of such motor cooling systems are that the suction gas is heated by the motors so that the compressors and their condensers have to be larger than they would be if suction gas was not used to cool the motors.

This invention takes saturated refrigerant gas from a condenser, cools the motor of the associated compressormotor unit with the saturated gas, and then returns the gas to the condenser. Using this motor cooling system, the size and the efiiciency of the associated compressor are not affected.

This invention will now be described with reference to the annexed drawings, of which:

FIG. 1 is a side view, with the condenser in section, of a refrigeration system embodying this invention, and

FIG. 2 is an enlarged cross-section through the motor of FIG. 1.

An electric motor has its rotary shaft 11 connected to a conventional speed-increasing gear-box 12 which drives a conventional, centrifugal, refrigerant compressor 13. The outlet of the compressor 13 is connected by tube 15 to the top of the interior of a shell-and-tube condenser 16 which contains spaced-apart, horizontal rows of tubes 17 through which water is circulated. The interior of the bottom of the condenser 16 is connected by a tube 19 to a conventional shell-and-tube evaporator 20 used as a water chiller. The outlet of the evaporator 20 is connected by a tube 21 to the inlet of the compressor 13.

Above the uppermost row of tubes 17 within the condenser 16 is a perforated bafile 22 for causing the discharge gas to be distributed uniformly across the upper row of tubes 17. There is -a pool 18 of condensed refrigerant liquid in the bottom of the condenser 16.

The electric motor 10 has a casing 25 with a circular opening 26 in the center of its top which is connected to one end of a tube 27, the other end of which is connected to the interior of the condenser 16 to one side of and above the uppermost row of the tubes 17. The casing 10 has a pair of circular openings 28 and 29 in its top near its ends, and which are connected to ends of tubes 30 and 31, respectively. The other end of the tube 31 opens into the tube 30, and the other end of the latter connects with the interior of the condenser 16 between the uppermost row of tubes 17 and the adjacent lower row of tubes 17, and to one side of the latter.

The motor 10 has a squirrel-cage type of rotor 33 on its shaft 11, and has a stator 34 and a stator winding 35 around the rotor 33. The stator 34 is supported from the casing by annular bars 36 which also space the stator from the casing to form an annular passage 38 around the stator, the center of which is aligned with the center of the central opening 26. The stator 34 has radial passages 40 connecting the annular space between the rotor and the stator with the annular passage 38. The casing 10 has end bearings 41 for the shaft 11.

In operation, the compressor 13 draws gas from the ores atnt Fatented Oct. 9, 1952 evaporator 20, compresses this gas, and pumps the completely condensed until it nears the bottom of the condenser, so that the gas below the uppermost row of tubes 17 of the condenser, would be gas which would be saturated with liquid refrigerant. This saturated gas passes through the tube 30 under its pressure, aided by the skin friction of the rotor 33 acting as a centrifugal pump, passes through the tubes 30 and 31 into the ends of the casing 10, passes through the open ends of the stator winding 35, over the surface of the rotor, through the radial slots 40 in the stator, into the annular passage 38, and then through the tube 27 to the interior of the condenser above the connection of the tube 30 to the condenser. The gas leaving the motor through the tube 27 is, of course, superheated by its absorption of heat fro-m the motor.

The condenser used in the cooling system of this invention would have to be larger than it would if the motor were not cooled, but no larger than a corresponding condenser used in a system for cooling a motor with suction gas, but the size and efliciency of the associated compressor would not be affected.

What is claimed is:

1. In a refrigeration system including a compressor, a shell-and-tube type of condenser having within its interior a plurality of vertically spaced-apart rows of gas cooling tubes, a discharge tube connecting said condenser above the uppermost row of said rows with the discharge side of said compressor, an evaporator, a liquid tube connecting the bottom of said condenser with the inlet of said evaporator, a suction tube connecting the outlet of said evaporator with the suction side of said compressor, an electric motor having a rotor connected to said compressor, said motor having a stator around and spaced from said rotor, having a casing around said stator with an annular passage between said casing and stator, said stator having radial slots extending therethrough aligned with said annular passage, said casing having an end passage between one of its ends and the adjacent end of said motor and connecting with the space between said rotor and stator, said annular and end passages having a partition therebetween for preventing gas from flowing from said end passage into said annular passage except through said space between said stator and rotor and said radial slots, the combination of a tube connecting said end passage with said interior of said condenser between said uppermost row of tubes and said bottom of said condenser for supplying saturated gas from said condenser into said end passage, and a tube connecting said annular passage with said interior of said condenser above where said last mentioned tube connects with said interior of said condenser for supplying gas heated by said motor into said condenser.

2. In a refrigeration system including a compressor, a shell-and-tube type of condenser having in its interior a plurality of vertically spaced-apart rows of gas cooling tubes, a discharge gas tube connecting said condenser above the uppermost row of said rows with the discharge side of said compressor, an evaporator, a liquid tube connecting the bottom of said condenser with the inlet of said evaporator, a suction tube connecting the outlet of said evaporator with the suction side of said compressor, an electric motor for driving said compressor, said motor having a rotor connected to said compressor, having a stator around and spaced from said rotor, having a casing around said stator with an annular passage between said stator and casing, said stator having radial slots extending therethrough aligned with said annular passage, said casing having an end passage between one of its ends and the adjacent end of said motor and connecting with the space between said stator and rotor, said annular and end passages having a partition therebetween for preventing gas from flowing from said end passage into said annular passage except through the space between said rotor and stator and said slots, the combination of a perforated baffle in said condenser between said uppermost row of tubes. and where said discharge gas tube connects with said interior of said condenser, a tube connecting said interior of said condenser between said bafiie and said uppermost now of tubes and said annular passage for 4 supplying gas heated by said motor into said condenser, and a tube connecting said end passage and said interior of said condenser between said uppermost row of tubes and the next adjacent lower row of tubes for supplying gas saturated with liquid into said end passage.

Moody Oct. 30, 1956 Moody v May 28, 1957 

